Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 23 Apr 2005

By SpaceRef Editor
April 23, 2005
Filed under , ,

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Apr 23 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 113 Issued at 2200Z on 23 Apr 2005

IA. Analysis of Solar Active Regions and Activity from 22/2100Z
to 23/2100Z: Solar activity continues at very low levels. There are
just a couple of very small and simple sunspot groups on the visible
disk. Occasional bright surges were observed on the southeast limb
late in the period. The associated active region is expected to
rotate into view on 24 April. No other activity of note was

IB. Solar Activity Forecast: Solar activity is expected to be very
low to low. A new region rotating on the east limb near S05 may
slightly elevate activity levels over the next three days.

IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z:
The geomagnetic field was quiet to unsettled with isolated active
conditions late in the period. A coronal hole high speed stream has
rotated into a geoeffective position. Solar wind speed gradually
increased to near 600 km/s. The IMF Bz was generally northward, but
occasional brief southward excursions occurred late in the period.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be quiet to unsettled with isolated active periods on 24
and 25 April. Predominantly quiet levels with isolated unsettled
periods are expected on 26 April as the high speed stream rotates
out of a geoeffective position.

III. Event Probabilities 24 Apr-26 Apr

  • Class M 01/01/01
  • Class X 01/01/01
  • Proton 01/01/01
  • PCAF green

IV. Penticton 10.7 cm Flux

  • Observed 23 Apr 079
  • Predicted 24 Apr-26 Apr 080/085/085
  • 90 Day Mean 23 Apr 090

V. Geomagnetic A Indices

  • Observed Afr/Ap 22 Apr 007/009
  • Estimated Afr/Ap 23 Apr 008/015
  • Predicted Afr/Ap 24 Apr-26 Apr 010/020-008/010-005/008

VI. Geomagnetic Activity Probabilities 24 Apr-26 Apr

A. Middle Latitudes

  • Active 30/25/15
  • Minor storm 15/10/05
  • Major-severe storm 05/05/01

B. High Latitudes

  • Active 40/35/20
  • Minor storm 20/15/05
  • Major-severe storm 10/05/01

SpaceRef staff editor.